The Humble Bundle library's checksums require two layers of looking-at-each-one-individually: first I need to click into a given game's library entry (of which only one is displayed at a time), and then I need to press the button next to the installer link to display its associated checksum. So it would be pretty difficult to scrape them into an easily-diffable format, I think.

(There does seem to be an unofficial Humble Bundle API which can return checksums for requested games, which would potentially be a solution if I were very desperate; but, between the API's lack of official support (and consequently spotty documentation) and my lack of experience with API programming, trying to do anything with it seems like a pretty daunting prospect.)